You can use a conjunctive adverb (also known as an adverbial conjunction) to join two clauses together. A conjunctive adverb is not strong enough to join two independent clauses without the aid of a semicolon.

The highlighted words in the following complex sentences are conjunctive adverbs:

The government has cut university budgets; consequently, class sizes have been increased.

He did not have all the ingredients the recipe called for; therefore, he decided to make something else.

The report recommended several changes to the ways the corporation accounted for donations; furthermore, it suggested that a new auditor be appointed immediately.

The crowd waited patiently for three hours; finally, the doors to the stadium were opened.

Batman and Robin fruitlessly searched the building; indeed, the Joker had escaped through a secret door in the basement.

An alternative method to creating a complex sentence is to create two simple sentences:

The government has cut university budgets. Consequently, class sizes have been increased.

He did not have all the ingredients the recipe called for. Therefore, he decided to make something else.